Controlling Watering of Bonsai with Cover During Summer Months

I live in central Connecticut, zone 6. I have 3 bonsai (1 tropical, 1 subtropical, and 1 outdoor). Currently, as of May 11, I am bringing the sub/tropicsls in at night.

I was told that I need to put them in a covered place (but sunny) during the summer months so I can control the amount of water they receive.

I realize this is an ideal situation, but I don't have any overhead cover. Is that what everyone does, or is it just this one person's opinion? If I need to cover them, does anyone have any ideas of how to do it other than building something (I don't have any tools to build anything fancy...) Thank you.

It is not going to hurt to leave any of them out without cover. When you water the temperate climate trees make sure they need the water. One of the beauties of Bonsai is the soil is porous enough to not hold too much water. In other words it takes lots and lots of water to create problems. That being said it is not impossible to over water. Water when things need it, not just to say that you watered.